He was never a douche!! He was a caring, sweet quirky person
I personally didn't feel that way in season 1, I found it such a sad move to go after a girl your best friend liked. Yes Hye Young was slow but he doesn't need the alarm to know he loves her. I understand why everyone's shocked about the outcome, I would be too.
If this was a real life situation and your best friend knew you liked someone and then went after them I personally wouldn't be very happy about it. I would say they have better chemistry but in the long run I think her and Hye Young suit better.
I think her picking Hye Young was the most logical decision. Although her and Sun Oh had chemistry you have to admit that he was a douche, especially in season 1. They're better off without each other.
If this was a real life situation and your best friend knew you liked someone and then went after them I personally wouldn't be very happy about it. I would say they have better chemistry but in the long run I think her and Hye Young suit better.